WASHINGTON (Reuters) - U.S. President Barack Obama’s administration has offered Saudi Arabia more than $115 billion in weapons, other military equipment and training, the most of any U.S. administration in the 71-year U.S.-Saudi alliance, a report seen by Reuters has found.

The report, authored by William Hartung of the U.S.-based Center for International Policy, said the offers were made in 42 separate deals, and the majority of the equipment has yet to be delivered. Hartung told Reuters the report would be made available publicly on Sept. 8.

The report said U.S. arms offers to Saudi Arabia since Obama took office in January 2009 have included everything from small arms and ammunition to tanks, attack helicopters, air-to-ground missiles, missile defense ships, and warships. Washington also provides maintenance and training to Saudi security forces.

The Center’s report is based on data from the Defense Security Cooperation Agency, a Department of Defense body that provides figures on arms sales offers and Foreign Military Sales agreements. Most of the offers, which are reported to Congress, become formal agreements though some are abandoned or amended. The report did not disclose how many of the offers to Saudi Arabia were agreed.

Washington’s arms sales to Riyadh recently have come under fire from rights groups and some members of Congress are disturbed by the rising number of civilian casualties in the war in Yemen, where a coalition led by Saudi Arabia is fighting Iran-allied Houthi rebels.

The conflict has killed at least 10,000 people. Last month the United Nations human rights office said that 3,799 civilians have died in the conflict, with coalition air strikes responsible for an estimated 60 percent of the deaths.

The coalition says it does not target civilians and accuses the Houthis of placing military targets in civilian areas. The coalition has created a body to investigate civilian casualties.

The outcry over those casualties has led some members of Congress to push for restrictions on arms transfers, and amid the growing outcry, the Pentagon cautioned that its support for Saudi Arabia in its Yemen campaign was not “a blank check”.

The Control Arms coalition, a group that campaigns for stricter arms sales controls, said last month that Britain, France and the United States were flouting the 2014 Arms Trade treaty, which bans exports of conventional weapons that fuel human rights violations or war crimes.

Hartung said the level of U.S. arms sales to Riyadh should give it leverage to pressure Saudi Arabia.

“It’s time for the Obama administration to use the best leverage it has - Saudi Arabia’s dependence on U.S. weapons and support - to wage the war in Yemen in the first place,” Hartung told Reuters.

“Pulling back the current offer of battle tanks or freezing some of the tens of billions in weapons and services in the pipeline would send a strong signal to the Saudi leadership that they need stop their indiscriminate bombing campaign and take real steps to prevent civilian casualties.”

Washington has been at pains to prove to Saudi Arabia and other Gulf allies that it remains committed to their defense against Iran in the wake of a multinational deal last year to restrict the Iranian nuclear program. Sunni Muslim Gulf states accuse Shi‘ite Iran of fomenting instability in the region, which the Islamic Republic denies.

“The more recent deals that have involved resupplying Saudi Arabia with ammunition, bombs, and tanks to replace weaponry used up or damaged in the war in Yemen are no doubt driven in part by the effort to ‘reassure’ the Saudis that the U.S. will not tilt towards Iran in the wake of the nuclear deal,” Hartung said.